import com.fasterxml.jackson.databind.ObjectMapper;
import com.mysql.jdbc.SQLError;
import com.mysql.jdbc.jdbc2.optional.MysqlDataSource;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.sql.DataSource;
import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

class Message {
    public String from;
    public String to;
    public String message;

    @Override
    public String toString() {
        return "Message{" +
                "from='" + from + '\'' +
                ", to='" + to + '\'' +
                ", message='" + message + '\'' +
                '}';
    }
}

@WebServlet("/message")
public class MessageServlet extends HttpServlet {

    private ObjectMapper objectMapper = new ObjectMapper();
    private DataSource dataSource=new MysqlDataSource();

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        Message message=objectMapper.readValue(req.getInputStream(),Message.class);
        System.out.println("请求中收到的messge："+message);

        try {
            save(message);
        } catch (Exception e) {
            throw new RuntimeException(e);
        }

        resp.setStatus(200);
        resp.getWriter().write("ok");

        
    }

    @Override
    public void init() throws ServletException {
        ((MysqlDataSource)dataSource).setUrl("jdbc:mysql://127.0.0.1:3306/ConfessionWall?characterEncoding=utf8&useSSL=false");
        ((MysqlDataSource)dataSource).setUser("root");
        ((MysqlDataSource)dataSource).setPassword("123456");
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setStatus(200);
        resp.setContentType("application/json;charset=utf8");
        List<Message> messageList=null;

        try{
            messageList=load();
        }catch (SQLException e){
            throw new RuntimeException(e);
        }

        String respJson= objectMapper.writeValueAsString(messageList);
        resp.getWriter().write(respJson);
    }

    private void save(Message message) throws SQLException {
        Connection connection=dataSource.getConnection();
        String sql="insert into message values(?,?,?)";
        PreparedStatement statement=connection.prepareStatement(sql);
        statement.setString(1, message.from);
        statement.setString(2, message.to);
        statement.setString(3, message.message);

        statement.executeUpdate();

        statement.close();
        connection.close();
    }

    private List<Message> load() throws SQLException {
        Connection connection = dataSource.getConnection();
        String sql = "select * from message";
        PreparedStatement statement = connection.prepareStatement(sql);
        ResultSet resultSet = statement.executeQuery();
        List<Message> messageList=new ArrayList<>();

        while(resultSet.next()){
            Message message=new Message();
            message.from=resultSet.getString("from");
            message.to=resultSet.getString("to");
            message.from=resultSet.getString("from");
            messageList.add(message);
        }
        resultSet.close();
        statement.close();
        connection.close();
        return messageList;
    }
}
